1. Field of the Invention
The present invention relates generally to a damper of a loudspeaker, and more particularly to a method of manufacturing a damper for a loudspeaker such that the damper manufactured accordingly has low formaldehyde content.
2. The Prior Arts
A damper is one component of the loudspeaker, also known as damping device or shock absorber or axis stabilizing plate. A conventional method of manufacturing a damper includes the steps of: immersing a piece of fiber cloth within a resinous solution; drying, formation and cutting-off processes, after which, a flexible damper is obtained.
However, it is noted that the resinous solution used for manufacturing of flexible damper contains highly toxic formaldehyde, which is classified as carcinogenic and teratogenic substances by World Health Organization (WHO). The toxic formaldehyde may cause some diseases to human health, namely dysosmia, irritation, allergy, pulmonary function abnormalities, liver dysfunction and immune dysfunction and so on. When the concentration of formaldehyde in the atmosphere reaches 0.06-0.07 mg/m3, children may suffer from slight asthma. When the indoor air contains formaldehyde content of 0.1 mg/m3, the smell is awful and one may feel discomfort and when it reaches 0.5 mg/m3, it may irritate the eyes, causing tears; up to 0.6 mg/m3 may cause throat discomfort or pain. At higher concentrations, the formaldehyde content can cause nausea, vomiting, cough, chest tightness, shortness of breath or pulmonary edema; and upon reaching 30 mg/m3 may cause immediate death to nearby living persons. Long-term exposure to low doses of formaldehyde can cause chronic respiratory disease, nasopharyngeal cancer, colon cancer, brain tumor, menstrual disorders in women, gene mutations, within the DNA single-strand DNA cross-linking, cross-linking of DNA and proteins, inhibition of DNA damage repair, pregnancy complications, neonatal chromosomal abnormalities, leukemia, and decline in memory and adolescent mentality. In all of the people who are exposed to formaldehyde, children and pregnant women are particularly sensitive to formaldehyde since the latter is more harmful to them.
Therefore, it is highly desired to develop and provide a method of manufacturing a damper for a loudspeaker, having low formaldehyde content, so that the residual formaldehyde content of the resin can meet safety standards in various countries. Hence, the concerned people are focusing on the field of the manufacturing.